After a relatively unsurprising series of primaries this month , June brings another collection of intraparty contests. More than half of the states will have selected their nominees by the end of the month. Republicans will pick nominees in key Senate races in Mississippi , Iowa and South Dakota. Down the ballot, House primaries in several open seats will likely determine the future members of Congress from both parties.

Here is Roll Call’s comprehensive look at watch to watch in June. Bookmark this page, and check out our primary map for results from past primaries.June 3 With primaries in eight states, this date marks the busiest night of the cycle.

Alabama: In the 6th District, seven Republicans are running in an open-seat race to replace retiring GOP Rep. Spencer Bachus. This district is located in and around Birmingham. State Rep. Paul DeMarco is the front-runner, followed by Club for Growth-backed surgeon Chad Mathis and businessman Will Brooke. If no candidate garners at least 50 percent of the vote, the top two candidates will continue to a July 15 runoff. Polls close at 8 p.m. EST. (Rothenberg Political Report/Roll Call Race Rating: Safe Republican )

California: In this House race battleground, the top-two vote recipients, regardless of party, advance to the general election. Republicans will also pick a gubernatorial nominee who could have an impact down the ballot in November. Polls close at 11 p.m. EST. Here are the primaries to watch in the Golden State:

7th District: Three Republicans are vying to challenge freshman Rep. Ami Bera, a Democrat, in this competitive Sacramento-based district. The national GOP's favorite is Rep. Doug Ose, but former Capitol Hill aide Igor Birman, who is backed by a number of tea party groups, also has a shot. (Rating: Leans Democratic)

25th District: A crowded primary field will try to succeed GOP Rep. Howard “Buck” McKeon in the northern Los-Angeles-based district. Podiatric surgeon Lee Rogers, a Democrat, is expected to take one of the top-two spots in this district. Two Republicans will likely battle for the second slot: state Sen. Tony Strickland, who lost a bid in the nearby 26th District last cycle, and state Sen. Steve Knight. (Rating: Favored Republican)

31st District: There could be an upset here Tuesday — again. Democrats want to pick-up this Inland Empire seat after the 2012 primary allowed two Republicans; including the eventual winner, now-retiring GOP Rep. Gary G. Miller; to advance to November (Obama scored a 17-point victory in the district). Democrats fret that former Rep. Joe Baca, D-Calif., could serve as a spoiler. But the most likely candidates to advance are Republican Paul Chabot and a Democrat, either attorney Eloise Gomez Reyes or Redlands Mayor Pete Aguilar. (Rating: Leans Democratic)

33rd District: In one of the most unpredictable primaries of the month, nearly two dozen candidates running to succeed retiring Democratic Rep. Henry A. Waxman. The district is home to wealthy celebrities who reside in and around Hollywood, Malibu and Beverly Hills. The top contenders are state Sen. Ted Lieu and former Los Angeles Controller Wendy Greuel — both Democrats — as well as Republican attorney Elan Carr and spiritual teacher Marianne Williamson, an independent whose views align with the Democratic Party. (Rating: Safe Democratic)

Senate: Rep. Bruce Braley is the de-facto Democratic nominee in this open-seat race, prompted by Sen. Tom Harkin's retirement. Five Republicans are vying for the nomination, but polling shows state Sen. Joni Ernst and former energy executive Mark Jacobs are the top candidates for the Republican nod. If no candidate garners at least 35 percent, the nominee will be decided at a June 14 convention. (Rating: Leans Democratic)

1st District: Five candidates are running for Braley's seat: State Rep. Pat Murphy, the former state House speaker, is the front-runner in the contest, which also has the possibility of heading to convention. But Democrats say Murphy would likely prevail in a convention too. (Rating: Safe Democrat)

3rd District: Republican Rep. Tom Latham’s retirement created an open-seat race. Former state Sen. Staci Appel is the likely Democratic nominee. There's a crowded Republican field, which is all but certain to head to a convention, including: State Sen. Brad Zaun, Iowa Secretary of State Matt Schultz, bridge construction contractor Robert Cramer, social conservative activist Monte Shaw and former Capitol Hill Aide David Young. Zaun, who ran a failed House bid in 2010, is the front-runner, but national Republicans say his nomination could imperil their chances of keeping the seat. (Rating: Tossup)

4th District: Down the ballot, former Democratic Rep. Gene Taylor is running as a Republican in the primary against Rep. Steven M. Palazzo, who defeated him in 2010. With three other Republicans also in the primary, there’s a shot it heads to a June 24 runoff — triggered when no candidate surpasses 50 percent. In either case, Taylor faces long odds to victory. (Rating: Safe Republican)

New Jersey: Democratic Sen. Cory Booker, who is currently serving out the late Sen. Frank R. Lautenberg's term, is up for a full term. But with no credible challengers in either party, Booker will cruise to victory in November. Instead, watch these two open House seats for primary action. Polls close at 8 p.m EST .

3rd District: Rep. Jon Runyan’s retirement sparked a competitive race in this district, located in the southern part of the Garden State near Philadelphia. Burlington County Freeholder Aimee Belgard is expected to win the Democratic nod. Republicans have a contested primary: former Randolph Mayor Tom MacArthur vs. former Bogota Mayor Steve Lonegan. MacArthur is the front-runner, but if Lonegan wins, he could cause Republicans problems in this competitive district. (Rating: Tossup)

12th District: Rep. Rush D. Holt’s retirement in the heavily Democratic seat sparked a crowded four-candidate Democratic field to replace him. The Democratic primary, which is likely to determine the next member of Congress from this Trenton-area district, is a close race between state Assemblywoman Bonnie Watson Coleman and state Sen. Linda Greenstein. (Rating: Safe Democrat)

New Mexico: At the primary level, there are no competitive contests that could have impacts in the Land of Enchantment in November. Polls close here at 9 p.m. EST.South Dakota: Democratic Sen. Tim Johnson’s retirement caused an open-seat race in the state for the first time in decades. Democrats failed to recruit a top-tier candidate, and Republicans will pick-up the seat in November, in all likelihood. Five Republicans are running for the GOP nod, but former Gov. Mike Rounds the clear favorite. Polls close at 9 p.m. EST. (Rating: Favored Republican )

June 10 Voters in five states will determine their House and Senate nominees on this primary night. Here's what to watch:

Maine: The 2nd District is an open-seat race, thanks to Democratic Rep. Michael H. Michaud's gubernatorial bid. State Sens. Emily Cain and Troy Jackson are vying for the Democratic nomination, and Cain is the favorite. On the Republican side, former state Senate President Kevin Raye will face former state Treasurer Bruce Poliquin, a tea-party-aligned candidate who is largely self-funding his bid. Polls close at 8 p.m. EST . (Rating: Democrat Favored )

South Carolina: GOP Sen. Lindsey Graham is up for re-election in November. While he is expected to win re-election, there is a chance that with a seven-candidate field he could be forced into a June 24 runoff. Runoffs in the Palmetto State are triggered when no candidate garners at least a majority of the vote. Polls close at 7 p.m. EST. (Rating: Safe Republican )

Virginia: The Senate primary will be uneventful: Democratic Sen. Mark Warner will face former Republican National Committee Chairman Ed Gillespie in November (Rating: Democrat Favored ). But further down the ballot, there are a few House primaries to watch. Polls close at 7 p.m. EST.

8th District: Democratic Rep. James P. Moran's retirement sparked a crowded Democratic primary for northern Virginia suburban seat. Former Lt. Gov. Don Beyer is the front-runner in the contest, but state Sen. Adam Ebbin and state Rep. Patrick Hope also have a strong base of support in the district. The winner has a clear path to election in November in this district. (Rating: Safe Democrat)

June 24Colorado: With no primary challengers, Democratic Sen. Mark Udall and GOP Rep. Cory Gardner will face off in November (Rating: Leans Democratic ). But Gardner's Senate bid opened up his seat in the 4th District. Four Republicans are running in that open-seat House contest, however Weld County District Attorney Ken Buck is the likely GOP nominee and next member of Congress from this strong Republican district (Rating: Safe Republican ) Polls close at 9 p.m. EST .

Maryland: A highly contested Democratic gubernatorial primary is taking place in Maryland this cycle, but there are no contested primaries in federal races this cycle. Polls close at 8 p.m. EST.New York: There are several competitive House primaries in the Empire State this cycle. Polls close at 9 p.m. EST .

13th District: Democratic Rep. Charles B. Rangel faces a tough primary against state Sen. Adriano Espaillat and Baptist Pastor Michael Walrond in the Harlem-based district. The primary threat is serious enough to give Rangel a spot on CQ Roll Call's list of the 10 most vulnerable members of Congress. (Rating: Safe Democrat)

21st District: Two Republicans are running for the GOP nomination to succeed retiring Democratic Rep. Bill Owens in this upstate seat. Former George W. Bush Aide Elise Stefanik faces attorney Matt Doheny for a spot on the Republican ballot line. But no matter who wins, both will appear on the ballot in November: Stefanik on the Conservative Party line, and Doheny on the Independence Party line. That could serve to spoil the GOP's chances here in November, when both face Democratic filmmaker Aaron Woolf. (Rating: Tossup)

Oklahoma: Sen. Tom Coburn's announcement that he will step down at the end of the year sparked a competitive Republican primary to serve out the rest of his term. Sen. James M. Inhofe is also seeking re-election in the primary, but he faces no significant opposition (Rating: Safe Republican ). Polls close at 8 p.m. EST .

Senate Special: Rep. James Lankford faces former state House Speaker T.W. Shannon in the race to replace Coburn, along with five other lesser-known Republicans. The large field could force the race to an Aug. 26 runoff, which happens when no candidate receives a majority of the vote. (Rating: Safe Republican)

5th District: Lankford's Senate bid forced a competitive primary for his Oklahoma City-based seat. Six Republicans are vying for that nomination: State Sen. Clark Jolley, state Rep. Mike Turner, former state Rep. Shane Jett, former state Sen. Steve Russell and State Corporation Commissioner Patrice Douglas. GOP operatives say the race is assured to head to a runoff, and Russell is the front-runner. (Rating: Safe Republican)